The hard part seems to be getting the machine shops to not only do the work correctly, but to do it at a reasonable cost, and to do it in reasonable time frame.As Paul and others spoke about there is a need for someone or some place that is proficient and knowledgeable in the performance and upgrade part of an engine, and has the contacts to get them done correctly.
The reasons I don't want to get involved with machine work are many. I still have work done locally, but the reality is I know the shop owners well enough that my stuff tends to sit around. I generally have to plan at least 6 months in advance. If I want the machine work on a cylinder head done by December, it has to go into the machine shop NOW!
There are other shops that can turn stuff around quicker, but they fall under two genres. The 'I'll get it to you as soon as possible' shops, where I just don't trust the labor they are doing, even though they are reasonably priced. And then the 'we'll have it done next month' shops that do very nice work....but you pay out the a** for the job. As much as 2-3 times the cost of the other shops!
I used to have all the machine work done locally on a big valve head for about $220. That shop is more expensive these days (they've grown in size and volume), but the turnaround time is horrible.
I know of two other shops that are excellent and have a great rep for quality, but they are on a 3-4 month backlog year-round and they are about $700 for the same exact labor procedures (albeit better-done and on nicer equipment).